Terahertz radiation is used in a wide variety of applications including airport security checks and material analysis in a lab. The wavelength of this radiation is significantly larger than the wavelength of visible light, as it is in the millimeter range. It also requires specialized techniques to manipulate the beams and get them into the right shape.

Unlike X-rays, Terahertz radiation is non-ionizing, which means that it will not affect the specimen it’s testing. This non-ionizing property has become increasingly important for many biological applications like testing that can be done in vivo, and as noted, in the lab or through a security check point.

At TU Wien, one of the major universities in Austria, shaping terahertz beams has been accomplished with resounding success with the help of a precisely calculated plastic screen produced on a 3D printer. They can now be formed into any shape necessary for any application.

According to Professor Andrei Pimenov from the Institute of Solid State Physics at TU Wien, it’s like lenses, only better.

“Normal plastic is transparent for terahertz beams, in a similar way as glass is for visible light,” he explains. “However, terahertz waves slow down a little when they pass through plastic. This means that the crests and troughs of the beam become a little displaced — we call that phase shifting.”

Phase shifting can be used to shape a beam. The light beams in the middle are more phase delayed than the light beams on the edge. This is precisely what causes the beam shape to change; a wider beam of light can then be focused onto a single point.

Jan Gosporadic, a PhD student on Pimenov’s team said, “We didn’t just want to map a wide beam to a point. Our goal was to be able to bring any beam into any shape.”

The shape change is achieved by inserting a precisely adapted plastic screen into the beam. The screen has a diameter of just a few centimeters, and its thickness varies from 0-4 mm. The screen’s thickness must be adjusted during each step so that the different areas of the beam are deflected in a controlled way, allowing for the desired image at the end. In order to obtain the desired screen design, they developed a special calculation method from which they can produce the matching screen via a 3D printer.

Using a 3D printer requires accuracy and reliability. At Universe Optics we specialize in designing and crafting precision lenses suitable for printing screens used to create the perfect terahertz beam.

At TU Wien, they believe their method is relatively easy to apply; and that the terahertz technology that is emerging will make it even more precise and more versatile.

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